CVE-2025-29448 is a high-severity vulnerability identified in Easy!Appointments version 1.5.1, a popular open-source appointment scheduling software. The flaw lies in the booking logic, where unauthenticated attackers can create appointments with excessively long durations. This manipulation causes a denial of service (DoS) condition by effectively blocking all future booking availability on the platform. The vulnerability does not require any authentication or user interaction, making it remotely exploitable over the network with low attack complexity. The vulnerability is categorized under CWE-284, indicating an authorization bypass or improper access control issue. By exploiting this flaw, attackers can disrupt the availability of the appointment system, preventing legitimate users from scheduling appointments. Although no known exploits are currently reported in the wild, the CVSS v3.1 score of 7.5 (high) reflects the significant impact on availability and ease of exploitation. The vulnerability does not affect confidentiality or integrity but solely impacts availability, which is critical for service continuity in appointment management systems. No official patch or vendor project information is provided, suggesting that users of Easy!Appointments 1.5.1 should be vigilant and consider mitigation strategies until a fix is released.

For European organizations relying on Easy!Appointments for scheduling client meetings, medical appointments, or service bookings, this vulnerability poses a substantial risk to operational continuity. The denial of service caused by booking excessively long appointments can halt business processes, degrade customer experience, and potentially lead to financial losses. Sectors such as healthcare, legal services, education, and small-to-medium enterprises (SMEs) that depend on appointment scheduling may face disruptions. Additionally, organizations with public-facing booking portals are more exposed, as attackers can exploit the vulnerability without authentication. The impact extends beyond direct service disruption; it may also damage organizational reputation and trust, especially where timely appointments are critical. Given the ease of exploitation and lack of authentication requirements, attackers could launch automated attacks at scale, amplifying the impact across multiple organizations. The absence of known exploits in the wild currently reduces immediate risk but does not eliminate the threat, particularly as public disclosure may prompt malicious actors to develop exploits.

Organizations should implement immediate compensating controls to mitigate the risk until an official patch is available. These include: 1) Implementing input validation and limiting appointment duration on the server side to prevent excessively long bookings. 2) Applying web application firewalls (WAFs) with custom rules to detect and block requests attempting to create unusually long appointments. 3) Restricting access to the booking interface via IP whitelisting or VPNs where feasible, reducing exposure to unauthenticated attackers. 4) Monitoring logs for abnormal booking patterns or spikes in appointment durations to detect exploitation attempts early. 5) If possible, temporarily disabling public booking features or requiring user authentication to create appointments. 6) Engaging with the Easy!Appointments community or maintainers to track patch releases and apply updates promptly once available. 7) Conducting internal security reviews of appointment scheduling logic to identify and remediate similar logic flaws proactively.